Survival in non-small cell lung cancer patients with versus without prior cancer

Clinical trials on cancer treatments frequently exclude patients with prior cancer, but more evidence is needed to understand their possible effects on outcomes. This study analyzed the prognostic impact of prior cancer in newly diagnosed non-small cell lung cancer (NSCLC) patients while accounting for various patient and cancer characteristics. Using population-based cancer registry data linked with administrative claims data, this retrospective cohort study examined patients aged 15-84 years diagnosed with NSCLC between 2010 and 2015 in Japan. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause mortality in patients with versus without prior cancer. The analysis was stratified according to NSCLC stage and diagnostic time intervals between prior cancers and the index NSCLC. We analyzed 9103 patients (prior cancer: 1416 [15.6%]; no prior cancer: 7687 [84.4%]). Overall, prior cancer had a non-significant mortality HR of 1.07 (95% CI: 0.97-1.17). Furthermore, prior cancer had a significantly higher mortality hazard for diagnostic time intervals of 3 years (HR: 1.23, 95% CI: 1.06-1.43) and 5 years (1.18, 1.04-1.33), but not for longer intervals. However, prior cancer in patients with more advanced NSCLC did not show a higher mortality risk for any diagnostic time interval. Smoking-related prior cancers and prior cancers with poorer prognosis were associated with poorer survival. NSCLC patients with prior cancer do not have an invariably higher risk of mortality, and should be considered for inclusion in clinical trials depending on their cancer stage.